In 2009, the FDA warned about possible skin burns due to transdermal drug delivery systems with metallic components that are maintained during Magnetic Resonance Imaging (MRI), cardioversion, or defibrillation procedures.1 In this sense, 2 adverse events were reported in which patients who were wearing a nicotine transdermal patch during an MRI experienced burns.2

Transdermal drug delivery systems with metallic components can be electrically conductive. Some patches are formulated with an aluminized backing that could potentially cause injury to the patient if worn during these procedures. MRI systems require the use of radiofrequency (RF) pulses to create the magnetic resonance signal. When conducting materials (i.e., aluminized backing) are placed within the RF field, the result may be a concentration of electrical currents sufficient to cause excessive heating and tissue damage.3,4

Despite the importance of this issue, information regarding the presence of conductive materials in the packaging of transdermal patches is usually lacking.

For this reason, the aim of the study was to review the presence of metallic components in marketed products of transdermal drug delivery systems.

In December 2022, marketed products of transdermal drug delivery systems were identified using the Spanish Agency for Medicines and Medical Devices database (https://cima.aemps.es/cima/publico/home.html).

For each product, 2 clinical pharmacists from a tertiary hospital reviewed the summary of product characteristics (SmPC) to confirm the need to remove the patch during MRI or other procedures. This information is usually specified as “the patch should be removed before the exposure to magnetic or electric fields” in section “4.4 Special warnings and precautions for use”. If this information was not given, the next step was to check section “6.1 List of excipients” to confirm the presence of metallic components. If they were not specified or they were only present in the liner, manufacturers were contacted by email. They were asked to confirm the presence of metals that could cause skin burns during MRI or other procedures. If no response was received after 1 month, a second follow-up was sent. If no response, the information was registered as “No reply from the manufacturer”.

This research did not include human participants and did not require ethical approval.

We identified 59 marketed products of transdermal drug delivery systems of 12 different active substances.

Information regarding the need to remove the patch before an MRI or other procedures was only included in 8 SmPCs (13.6%).

59.3% of patches contained metallic components or their absence could not be confirmed by the manufacturer (33.9% and 25.4%, respectively) (Table 1).

A table was elaborated and included the following aspects: active substance, product, manufacturer, need to remove the patch before the exposure to magnetic or electric fields, and references (Table 1).

To our knowledge, this is the first study that analyzes the presence of metallic components in marketed products of transdermal drug delivery systems. Some authors have alerted about the risk of serious skin burns associated with the use of patches but none of them have carried out a comprehensive review of their composition.3,4

Several safety issues have been notified with the use of transdermal drug delivery systems, such as errors in the frequency of application or overdosing after cutting the patch.5,6 The need to remove transdermal patches with metallic content before some procedures to prevent skin burns is not well known and could put patients at risk. It is of paramount importance that patients and healthcare professionals be aware of this precaution. In this sense, Radiology, Cardiology, and Emergency Departments should develop safety recommendations regarding the use of patches for patients receiving an MRI, cardioversion, or defibrillation procedures. In our institution, protocols were updated with the information obtained from this review. Currently, patients are questioned about the use of any transdermal patch and, unless it is certain that the patch does not contain metal, patients are counseled to remove it temporarily to avoid unnecessary burns. We believe that the data we compiled can be useful in other healthcare environments to prevent patient harm.

Surprisingly, only 13.6% of available SmPCs included the precaution to remove the patch before an MRI. However, in more than half of the pharmaceutical forms, metallic components were present or could not be excluded. We believe that this cautionary information should be compulsorily included in SmPCs whenever a new patch is authorized by a regulatory agency. The document published by the EMA “A Guideline on Summary of Product Characteristics” establishes that the content of section “4.4 Special warnings and precautions for use” of SmPC should include any information regarding a specific risk when this risk leads to a precaution for use or when healthcare professionals have to be warned of this risk, in our case, skin burns when the patient undergoes an MRI or other procedures.7 Moreover, in section 6.1, all ingredients of the patch (including the adhesive, release liner, and backing film) should be mentioned. However, we found several cases (i.e., Buprenorphine SANDOZ) in which the SmPC did not mention any aluminized component but the manufacturer confirmed its presence.

The main limitation of this study is that the review was performed for transdermal drug delivery systems that were marketed at the time of the study.

More than a half of the patches at the time of the study contained metals or their absence could not be confirmed by the manufacturer. However, this information was only included in 13.6% of SmPC.

- Skin burns are associated with the presence of metallic components in transdermal drug delivery systems during Magnetic Resonance Imaging, cardioversion, or defibrillation procedures.

- To our knowledge, this is the first study that analyzes the presence of metals in marketed products of transdermal drug delivery systems.

- Information regarding the need to remove the patch before an MRI or other procedures was only included in 13.6% of the summaries of product characteristics.

- We believe that this comprehensive review could be useful to every healthcare environment to prevent harm when a patient needs to undergo any of these procedures.

- Ana de Lorenzo-Pinto: conception and design of the work, data collection, analysis and interpretation of the data, writing of the article and approval of the final version for publication.

- Carmen Redondo-Galán: data collection, analysis and interpretation of the data, writing of the article and approval of the final version for publication.

- Xandra García-González: data collection, critical revision with important intellectual contributions, writing of the article and approval of the final version for publication.

- Carmen Fernández-Álvarez: critical revision with important intellectual contributions and approval of the final version for publication.

- Juan Andueza-Lillo: critical review with important intellectual contributions and approval of the final version for publication.

- María Sanjurjo-Sáez: critical revision with important intellectual contributions and approval of the final version for publication.

None.

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Ana de Lorenzo-Pinto: Conceptualization, Data curation, Formal analysis, Methodology, Validation, Writing – original draft, Writing – review & editing. Carmen Redondo-Galán: Data curation, Formal analysis, Investigation, Methodology, Supervision, Writing – original draft. Xandra García-González: Conceptualization, Data curation, Supervision, Validation, Writing – original draft. Carmen Fernández-Álvarez: Investigation, Supervision, Validation. Juan Andueza-Lillo: Supervision, Validation. María Sanjurjo-Sáez: Supervision, Validation.